The object of the present study was to evaluate, with the aid of visual evoked potentials (VEPs), modifications induced in the optic nerve by lead, and to investigate the relationship between blood lead levels (PbB) and modification of the VEP. We studied a sample of 300 men with PbB values between 17 and 60 micrograms/100 ml. Our study demonstrates that alterations in the latency of the VEP are dependent on PbB levels, though there is not a directly proportional relationship.